Question

Please I need help!!!!

Answer 1

#1

• y=x²-18x+88

x coordinate of vertex

• -b/2a
• 18/2
• 9

y coordinate

• y=9²-18(9)+88
• y=81+88-162
• y=7

Option C.

#2

• y=x²-9x-36

y intercept

• y=0-36=-36

(0,-36)

x inetercepts

• x²-9x-36=0
• x²-12x+3x-36=0
• (x-12)(x+3)=0
• x=12,-3

(12,0)U(-3,0)

#3

• y=-x²+3x+12

Find dy/dx

• -2x+3

f'(x)=0<=>x=3/2

For increasing

• -2x+3>0
• x<3/2

For decreasing

• x>3/2

F(x) is increasing on (-oo,3/2)

F(x) is decreasing on (3/2,oo)

• D

Answer 2

1st

Vertex

we have

f(x)=x²-18x+88

let

y=x²-18x+88

comparing above equation with ax²+bx+c

we get

a=1

b=-18

c=88

now

vertex(x,y)=(-b/2a,f(-b/2a))

x=(18/2×1)=9

y=f(9)=9²-18×9+88=7

SO

VERTEX(X,Y)=(9,7)

=